Rehearsal Dinner Slideshow Length?

Short like a trailer maybe 15 mins at most. If not 10 or 5.

That's my opinion.

Do you want the slide show to be in the background, or will your guests be asked to stop what they are doing and give their undivided attention to the slide show?

If you want them to sit and watch, I would make it no more than 5 minutes. If it is just in the background, and guests can watch yet keep chatting with each other, then 10-15 minutes.

I would like if they watched the slide show, but I won't get offended if they randomly glance up to it and then go back to talking. I was thinking 5-6.5 minutes would be a good time line if it's something that I wanted people to pay more attention to rather than not pay attention to.

Bumping to help you out @Cassie I

I think 3 - 5 minutes if they have to stop. But I do recommend it just run in the background on a loop even. Toward the end of the RD, people have gotten into their logical groupings and may be having good times and conversations or even dancing (if that's how you flow). A slide show viewing will mess with the overall feel.

If you are going to stop and have folks watch, I say do it earlier in the evening.

I would say about the length of 1-2 songs worth (assuming you are putting to music)